The contents of photosynthetic pigments in the colored forms of cacti in comparison with other succulent plantsI.M. Skoulkin, Ph.D and E.P.Artemyeva

фото 1.

The purpose of the work is to check the following hypothesis: all the abnormal colored forms (ACF) of cacti are real chlorophyll-free mutants.

The tasks of the research are:

To determine the presence of photosynthetic pigments in ACF;

To compare the quantity of chlorophyll and carotinoids in ACF, stocks, succulents and common plants;

Evaluation of ration "chlorophylls to carotinoids" and "chlorophyll a to хлорофилл b" in ACF in comparison with 3 control groups.

фото 2.

Materials and methods. In summer 2000 we started the research of the contents of photosynthetic pigments - chlorophylls a and b and carotinoids in 9 different ACF of cacti including Eriocactus magnificus f. aurea, Chamaecereus silvestrii f. aurea, and 6 forms of Gymnocalycium mihanovichii var. friedrichii.

As there is no universal system of ACF names we used our own names based on the ACF's coloring at the moment of research:

BLACK - a dark brown form with pinkish fragments (most probably this is "Black Botan")(photo 6).

фото 3.

We also included growing on its own roots Gymnocalycium mihanovichii var. friedrichii s.str., a species that served as the base for most ACF Gymnocalyciums.

For comparison we took 7 species of cacti usually used as stocks (Hylocereus, Selenicereus and others), 18 species of succulents of Crassulaceae family and 3 species of non-succulent plants (lily-of-the-valley, oxalis, amaranth). All the plants except the 3rd group were kept for two month before the research in the greenhouse with the temperature about +30 °С in good natural lighting conditions.

фото 4.

We researched only the outer parts of the rind of the cacti together with epidermis 1.5 - 2 mm thick as the main part of the pigments is situated in this zone.

As for succulents, we took mainly the fragments of the middle part of the leaves.

The samples were fixed, then crumbled up to have the pigments extracted with 85% acetone. The concentration of the pigments was determined by spectrophotometer "Lomo" SF-46. The results were checked three times for all the species.

фото 5.

RESULTS AND DISCUSSION. Out of 4 groups of the studied plants the least quantity of chlorophylls was found in ACF cacti (table 1). Succulents of Crassulaceae family had a bit more. Stocks had about twice more green pigment. And deciduous plants, mainly heliophobe, had an order higher contents of chlorophylls which correspond to the known data.

We also included growing on its own roots Gymnocalycium mihanovichii var. friedrichii s.str., a species that served as the base for most ACF Gymnocalyciums.

фото 6.

For comparison we took 7 species of cacti usually used as stocks (Hylocereus, Selenicereus and others), 18 species of succulents of Crassulaceae family and 3 species of non-succulent plants (lily-of-the-valley, oxalis, amaranth). All the plants except the 3rd group were kept for two month before the research in the greenhouse with the temperature about +30 °С in good natural lighting conditions.

We researched only the outer parts of the rind of the cacti together with epidermis 1.5 - 2 mm thick as the main part of the pigments is situated in this zone.

As for succulents, we took mainly the fragments of the middle part of the leaves.

The samples were fixed, then crumbled up to have the pigments extracted with 85% acetone. The concentration of the pigments was determined by spectrophotometer "Lomo" SF-46. The results were checked three times for all the species.

Table 1

The Contents of pigments (mg/g of raw weight) and their ratio in succulent and non-succulent plants

We found almost no difference in the contents of yellow and red pigments, that are carotinoids, in ACF cacti, stocks and Crassulaceae. It means that the coloring of the colored forms of cacti is not connected with the high contents of carotinoids in cacti as compared to other succulents.

The comparative analysis of the different ACF is given in Table 2.

Table 2.

The contents of pigments and their ration in colored forms of cacti and the initial species Gymnocalycium mihanovichii var. friedrichii s.str. (ranged according to the contents of chlorophyll А+В)

№

Form

Part of the plant

А+В

С

А+В+С

(А+В):С

А:В

1

MULTICOLOR (HIBOTAN)

Black shoot 7 мм

1,54

0,58

2,12

2,55

2,15

2

MULTICOLOR (HIBOTAN)

Bud

1,09

0,34

1,43

3,20

1,97

3

BLACK

Young tissues

0,88

0,41

1,29

2,15

3,04

4

MULTICOLOR (HIBOTAN)

Orange shoot 7 мм

0,83

0,43

1,25

1,94

0,67

5

MULTICOLOR (HIBOTAN)

Young tissues

0,73

0,39

1,13

1,63

2,32

6

BLACK

Bud

0,50

0,18

0,69

2,73

1,88

7

MULTICOLOR (HIBOTAN)

Shoot 15 мм

0,50

0,38

0,87

1,27

4,24

8

MULTICOLOR (HIBOTAN)

Shoot 15 мм

0,48

0,42

0,91

1,05

3,70

9

Gymnocalycium friedrichii s.str.

Seedling 1 год

0,45

0,36

0,82

1,25

0,53

10

Eriocactus magnificus AUREA

Young tissues

0,35

0,06

0,41

6,08

3,05

11

PURPLE

Shoot 7 мм

0,13

0,19

0,33

0,66

0,53

12

Chamaecereus silvestrii AUREA

Young tissues

0,11

0,12

0,23

0,86

3,15

13

ROSE

Shoot 15мм

0,11

0,08

0,19

1,12

1,11

14

PINK

Shoot 7 мм

0,10

0,02

0,12

5,63

ошибка

15

MULTICOLOR (HIBOTAN)

Old tissues

0,10

0,16

0,26

0,57

0,54

16

PINK

Bud

0,07

0,03

0,10

2,41

2,17

17

RED

Shoot 7 мм

0,04

0,19

0,23

0,15

0,63

Average in the group

0,47

0,25

0,73

2,07

1,98

Standard deviation

0,43

0,17

0,57

1,65

1,22

фото 8.

Such ACFs as MULTICOLOR and ВLACK contain much more chlorophyll than growing on its own roots initial species Gymnocalycium mihanovichii var friedrichii. It means that such ACFs should not be called "chlorophyll-free" and even "low-chlorophyll". Probably they do not need grafting. They can be grown on their own roots. All other ACFs contain much less chlorophyll than Gymnocalycium mihanovichi var. friedrichii. Perhaps, only dark-red ACF "RED" can be called with reserves "real chlorophyll-free".

CONCLUSIONS

The colored forms of cacti have abnormally low contents of chlorophylls. The succulents of Crassulaceae family have slightly more of them, meanwhile, the deciduous plants have an order higher contents of chlorophylls.

The contents of carotinoids in colored forms, stocks and Crassulaceae practically do not differ. It proves that the coloring of the colored forms of cacti in general and its intensity in particular is not connected with the high contents of carotinoids. The contents of carotinoids and the pigments in sum are also an order higher.

The ratio "chlorophyll : carotinoids" is the smallest in the colored forms of cacti and very small in general. The difference of this characteristic in stocks, Crassulaceae and deciduous plants is not significant. Cacti stocks are closer to Sciophytes, and Crassulaceae have an intermediate position between Heliophytes and Sciophytes

The ratio "chlorophyll a: chlorophyll b" is significantly lower in colored forms as compared to stocks and deciduous plants, though there is not much difference with Crassulaceae.

We found significant differences of pigments contents and their indices in different parts of the same plant. The vivid example is ACF MULTICOLOR. The contents of the pigments in shoots are higher than in the young tissues of the maternal plant where it is 5 to 6 times higher than in deeper 4 to 5 years old tissues. This data proves the idea of quick ageing of colored forms when the contents of photosynthetic pigments go down quickly.

It is incorrect to call most colored forms "chlorophyll-free" as there are chlorophylls in them. Sometimes their quantity is insignificant but sometimes it is bigger than in the initial plant growing on its own roots (Gymnocalycium mihanovichii var. friedrichii.)